1. Field of the Invention
The present invention relates to a copper clad aluminum wire, a compressed conductor and a cable including the same, and a method of manufacturing the compressed conductor, and more specifically, to a copper clad aluminum wire which can exhibit electrical features similar to those of a conventional pure copper wire without greatly increasing an outer diameter, a compressed conductor and a cable including the copper clad aluminum wire, and a method of manufacturing the compressed conductor.
2. Background of the Related Art
As the cost required for purchasing copper, which is an important material of a cable conductor, rises greatly in recent days with the increase of international copper and raw material prices, materials that can substitute for the copper from the aspect of price and performance, while exhibiting electrical features similar to those of copper, are required increasingly.
The biggest problem in developing a substitute material is that it is difficult to secure a material having sufficient reliability in mechanical and physical features so as to be used as a cable conductor, while maintaining electrical features similar to those of copper.
Electrical features, physical features and connector-related features are basis of product design in developing materials of cable conductor, and studies on developing a material satisfying these features and applying existing materials to a cable are under progress.
Particularly, since materials of a conductor generally have a proportional relationship between electrical features and prices of raw materials in many cases, most of substitutable materials have electrical features inferior to those of copper if their prices are low, and if electrical features the substitutable materials are excellent, their prices are high.
Materials used for a cable conductor are generally limited to copper, aluminum, silver or an alloy of these having a high conductivity. The other materials have electrical features considerably inferior to those of the materials described above, and although their electrical features are excellent, prices of raw materials are too high, and thus they are inappropriate to be used as a material of an industrial cable.
The copper which is most frequently used as a cable conductor in the prior art has been used as an important material for a long time owing to high electrical conductivity and low price which are the most optimum conditions as a material of a cable conductor.
However, as the price of copper increases three times or more than ever before due to increase in prices of raw materials, studies on using aluminum or the like of a low price as a conductor material are under progress although its electrical features are inferior to those of copper.
However, if the aluminum is used as a cable conductor, a problem of generation of an oxide film which hinders electrical conductance due to a fast reaction rate, problems occurred by the heat relatively greater than that of copper, and a problem of the cross-section which increases to be larger than that of copper due to the inferior electrical features when it is used as a cable conductor, in addition to the problem of electrical features inferior to those of copper, will be confronted.
Sine an aluminum alloy also has problems similar to those described above, a copper clad aluminum (CCA) wire, which is a wire formed by wrapping a copper strip around an aluminum rod, has been proposed as an alternative to the aluminum alloy.
Since the electrical features of the copper clad aluminum wire are between the features of copper and aluminum, and the problem of generation of an oxide film, which is the most serious problem in applying the aluminum, does not occur, the copper clad aluminum wire is studied as an alternative for substituting the copper as a composite material.
Particularly, according to the specifications of the American Society for Testing Materials (ASTM), the copper clad aluminum wire is standardized to have a copper volume ratio of 10 to 20%, and manufacturing companies mass-produce copper clad aluminum wires having a copper volume ratio of 15 to 20%.
Features of the copper clad aluminum wire, which are degraded compared to those of copper when the copper clad aluminum wire is used as a cable material, are largely divided into electrical conductivity and mechanical features, and the electrical features can be improved according to resistance formulas as the cross-section is increased. That is, since the copper clad aluminum wire has a high wire resistance compared with that of the copper, it should have a diameter considerably larger than that of the copper in order to have a resistance similar to that of the copper.
However, if the outer diameter of the copper clad aluminum wire increases, the outer diameter of the cable also increases. Although the diameter of a conductor is not increased greatly in the case of a solid-type cable such as a conventional coaxial cable applying the copper clad aluminum wire, when the copper clad aluminum wire is applied to a power supply cable of a large diameter, increase of diameter will be a negative factor from the aspect of cable performance.
It is since that if a cable has electrical features the same as those of copper and its weight is relatively light considering specific gravity although its volume is increased compared with that of the copper, a cable having a smaller diameter is advantageous from the aspect of work convenience of a worker who installs the cable and utilization of an installation space.
However, when a cable is manufactured using a conductor which strands existing mass-produced copper clad aluminum wires having a copper volume ratio of 15 to 20%, the diameter of the conductor itself is increased greatly, and the diameter of the cable using the conductor also increases as a result, and thus it is difficult to have an outer diameter similar to that of an existing conductor of a copper material.
Accordingly, it is required to provide a copper clad aluminum wire which can exhibit electrical features similar to those of a conventional pure copper wire without greatly increasing outer diameters of a conductor and a cable.